i am trying django-selectable the 'fruit' example given in the docs here -
https://django-selectable.readthedocs.org/en/version-0.6.2/quick-start.html#defining-a-lookup
getting LookupAlreadyRegistered error,there is a small note on this error,but i can't
figure out how to solve this.i understand that it has something to do with import statements, i am using django-1.3
i will provide more info if needed , but i am just using the same code as given in the example.
kindly help
Check the note in the link you've posted:
You should only register your lookup once. Attempting to register the same lookup class more than once will lead to LookupAlreadyRegistered errors. A common problem related to the LookupAlreadyRegistered error is related to inconsistant import paths in your project. Prior to Django 1.4 the default manage.py allows for importing both with and without the project name (i.e. from myproject.myapp import lookups or from myapp import lookups). This leads to the lookup.py file being imported twice and the registration code executing twice. Thankfully this is no longer the default in Django 1.4. Keeping your import consistant to include the project name (when your app is included inside the project directory) will avoid these errors.
Related
I have a few defined apps in my Django project, each with their own sub-directory (created with startapp)
In the views.py of app1 I have an import to a model from app2
from app2.models import MyModel
This worked in Django 1.6.x. In version 1.9 I get:
Could not resolve variable
sometimes on MyModel, sometimes on the filter(..) method, or on both.
If I change the import to
from app2.models import * ##UnusedWildImport
then everything works just fine.
Has anything changed in 1.9.x (or before) that requires a different mode of importing models external to the app?
I think I can rule our circular import problems as this would have failed in 1.6...
Edit: Based on the comments I started wondering whether this might be a PyDev problem.
I tried:
Removing and re-adding Python to PyDev - it did not help
This https://stackoverflow.com/a/8534599/5958359 - removing the myproject/src folder from PYTHONPATH worked ... with a caveat.
The error did not appear when I completely removed the import statement, so this is not a good solution
This is a PyDev error.
Searches haven't yielded an adequate solution - most simply explain how to disable the error - so I will not link to any solution here.
My workaround, as much as I don't like from xxx import * seems like the best temporary solution.
OK -- I've been working with Django for a few months now and have come across a weird issue. To set it up, here's my webapp structure.
The main Django project is called cpm.
I have a bunch of django apps in the cpm folder. Within each app, I have my models.py file.
Now, when I want to create/use models from other apps I would do something like:
from cpm.products.models import *
assuming an app named products was present. Recently, I started to get some errors saying things like, cannot import XYZ from products. So, after much searching, I changed the line:
from cpm.products.models import *
to
from products.models import *
I just dropped the cpm. part and now it works.
Can someone tell me why this is happening? It seems to be happening on only portions of my apps (I have a bunch within the CPM project). I want to make sure my syntax is accurate as I move forward.
Thanks!
The project root's directory got removed from the python path somewhere along the way, or you removed the __init__.py file from it's root.
On a side note, importing * will lead to issues, especially when you start adding lots of apps. Consider doing from products import models as prod_models. Then doing prod_models.MyModel where you need to reference your models.
I followed this post here and sorted out how to set the ForeignKey of one model to a model in another application. However, when I try it a second time I get an error and not sure why.
I have Central app with models for a 'project' and an 'annotation', and a Reports app with a report model. An 'annotation' has a FK to a 'report' in the Reports app, and that seems to work fine with this code:
#models.py for Central app
from GIanno.pt_reports.models import Report
class annotation(models.Model):
...
report=models.ForeignKey(Report)
But, in the Reports app, when I try to set a FK for the 'report' to link it to a 'project' from the 'Central' app using the same format as above, I get an error "cannot import name 'project' from the import line.
Any ideas on why it works one way and not the other. Does order somehow matter? Thanks
My guess is that you have created a circular import condition. This occurs when you import something from one python module which in turns imports from the module which is trying to import it, thus preventing the import from ever resolving.
In general there are three strategies for dealing with circular imports, two of which will work in this case:
Move around your classes and imports so that the imports only go one direction.
Use lazy evaluation. In Django's case this can be accomplished for a ForeignKey by passing a string specifying the app name and model using dot notation: report=models.ForeignKey('central.Report')
Move the import statement out of the global module scope and into the scope of a function within the module. That way the import isn't evaluated immediately and the module can be successfully imported as a whole while still allowing the import within the module to happen when it's called. (Note: this won't work for ForeignKey relationships)
The lazy FK resolution (#2) is probably your best bet here. In general, though the best strategy is to simplify your model/module arrangement to avoid circular imports whenever possible.
Try:
class annotation(models.Model):
...
report=models.ForeignKey('centralapp.Report')
Replace 'centralapp' with name of your central app name without needing to import.
Lazy Relationships
Another scenario where the Lazy Relationships might be useful is with import order. It's not a circular reference (where it can't tell who's first) but a case where one piece of code is loaded before the other can be.
For example, let's say I have a Doc Model and a Log Model. The Log model has a FK for the Doc so I can record changes in the document. This works fine until, let's say, I try to generate a Log record in my save method for my Doc model (to make a save event log entry). There is no Log PK in the Doc object in this case but is a similar issue.
In this case you get an import order problem, where one will try to reference something that has not been loaded into Python yet. It's similar to a Circular Reference but a different cause.
This can be solved other ways but is another example where you will run into this problem.
I'm having a headache with some errors that appear suddenly on an application I'm developing. One time I solved it using complete imports (including the project dir) but this time the error has no sense.
TemplateSyntaxError at /accounts/login/
Caught ViewDoesNotExist while rendering: Could not import e_cidadania.apps.proposals.views. Error was: cannot import name User
And marked code is:
{% trans "Lost your password?" %}
The import line at views.py:24
from django.contrib.auth.models import User
I must say, 24h before everything was working fine and no changes were made to the repo.
I've looked the url and the view, both are fine. I've run manage.py shell and tested the import, works fine. I did put some markers in the code to test how it was running and the program crashes exactly importing the User model in that file (there are lots of imports User in the application and not one of them gave a warning). Even deleting the import from thefile gives the same error!
How can I track this to know what is the real problem?
UPDATE: I forgot to mention that the marked error is in the userprofile module, and the proper error is given in the proposals module, a module that has absolutely nothing to do with userprofile.
UPDATE 2: You can see the code here, the application is GPL so there is no problem.
The "relation" between userprofile and proposals modules is that you probably refer to both in the urls definition, which is used to do the reverse when using {% url 'whatever.viewname' [args] %} there probably you do import some view function from both.
I would start having a look at modules you're importing there.
I had this annoying problem (more than once) and most of the time it was caused by recursive imports or by a order dependent imports that I was not aware of (because most of the times "was working").
I've been doing a little clean up on my django project and so I decided to rename some models remove some unnecessary fields etc. I dropped all the tables from the dbase and reran "syncdb". However, now I'm getting and error
Could not import pollsite.polls.views. Error was: cannot import name OldTableName
Its a template error from base.html
OldTableName doesn't exist anymore (I've renamed it). Is there something else I need to run to get the admin site to work properly with the new schema?
You need to check your imports in your pollsite.polls.views. Most likely you still have an import of the old model name in that file.